Field of the Disclosure
The present disclosure relates to an electrophotographic roller for use in an electrophotographic apparatus adopting electrophotography, such as a laser printer, a copying machine, or a facsimile, a production method for the electrophotographic roller, and an electrophotographic apparatus.
Description of the Related Art
With recent improvements in speed and durability of electrophotographic apparatuses, electrophotographic rollers used in the electrophotographic apparatuses are required to have higher accuracy and higher durability. Here, a typical example of an electrophotographic system obtains an image through a step of applying potential to a surface of a photosensitive member using a photosensitive (photoconductive) substance (charging step), a step of forming an electric latent image by partly exposing the surface of the photosensitive member (exposure step), a step of developing the latent image with toner into a visible toner image (developing step), a step of transferring the toner image onto a recording material such as paper (transfer step), and a step of fixing the toner image on the recording material by heat and pressure (fixing step). A supplementary step, for example, a step of removing toner base particles and external additives, which are not transferred onto the recording material, but remain on the surface of the photosensitive member, from the surface of the photosensitive member by various methods (cleaning step) is sometimes added.
In these steps, an electrophotographic roller having an elastic layer is generally used. By rotating the electrophotographic roller, toner, external additives, and paper dust are prevented from being locally attached to the electrophotographic roller. This reduces image defects.
While such an electrophotographic roller generally has an elastic layer on a solid base, it has been proposed to use a cylindrical base instead of the solid base for the purpose of weight and cost reduction. For example, Japanese Patent Laid-Open No. 2006-289496 proposes to use a cylindrical shaft (cylindrical base) formed by bending a metal plate instead of the solid base.
The cylindrical base has a joint extending from one end to the other end in its longitudinal direction, and the joint sometimes has a gap (groove). Japanese Patent Laid-Open No. 2007-025196 proposes to form an elastic layer after filling a gap in a joint with filler. In this case, unevenness of conveying speed of a recording material is rarely caused by thermal expansion in the joint of the cylindrical base. Also, when the elastic layer is formed, the material of the elastic layer is prevented from leaking to the inside of a hollow shaft through the gap. Japanese Patent Laid-Open No. 2010-184806 proposes that, when a high-friction layer containing inorganic particles is formed, a gap is filled with fine inorganic particles. This avoids unevenness of the conveying speed at the joint, and prevents the material of the inorganic particles from entering the inside of a hollow shaft through the gap.